Web support



Oct. 3; 1967 G. SWINDELLS 3,344,774

WEB SUPPORT Filed June 29, 1966 FIG! jiva/z/vrae $20 666 (Siam/51.45

United States Patent 3,344,774 WEB SUPPORT Geoffrey Swindells, Hyde, England, assignor to Imperial Chemical Industries Limited, London, England, a corporation of Great Britain Filed June 29, 1966, Ser. No. 561,577 Claims priority, application Great Britain, June 29, 1965, 27,490/ 65 1 Claim (Cl. 118500) This invention relates to a web support for use in the application of coating compositions to webs.

Commonly webs, for example fabrics, have been provided with a coating of a coating composition by a technique which has involved passing the web continuously under an applicator device, such as a doctor knife or rotating roller, which serves to maintain a bank of coating composition on the web and applies a coating on to the web as it passes thereunder. Invariably the web is provided with a support as it passes under the applicator device. Usually the web support consists of a natural or synthetic continuous rubber band having a greater transverse dimension than the web and which is conveniently rotated in such a direction as to aid the motion of the web. The web support provides a generally flat resilient support against which the underside of the web is maintained in abutment during the coating process.

It has been found with such supports that, though they function adequately when first used, their useful life is limited. This has mainly been due to attack by the coating compositions used which inevitably come into contact with the support either by penetration through the web, when the web is porous, or by seepage over the edge or selvedge of the web used. This has resulted in a swelling of the resilient support with the result that its surface is rendered uneven which causes non-uniform depths of the coating composition to be applied on the web.

In accordance with the present invention a web support for use in the application of coating compositions to webs comprises a stationary sheet member, constructed from a material which is resistant to attack by the coating composition used, over the surface of which passes the web to be coated, said sheet member being supported by means which provide resilience normal to the plane of the web.

Though for a number of applications of our invention it is suitable for the sheet member to be non-flexible it is preferred that it is flexible.

Typically our sheet member is made from sheet steel in which case a suitable thickness for the member can be selected in the range 0.005 inch to 0.025 inch. Alternatively any other suitable material may be used, for example, wood or plastic.

Essentially in our invention the sheet member is substantially flat over at least that part of its surface immediately beneath the applicator.

The resilient support means serves to allow vertical movement of the sheet member when the latter is subjected to vertical forces which are applied during a coating operation, especially when faulty or uneven webs are being coated. It will be realised that the vertical forces applied during the coating operation will vary a great deal from one web material to another and in view of this the resilient support means for use in our invention is chosen with the particular web material to be used in mind. When the web is a fabric a suitable resilient support means comprises one or more layers of a polyurethane or other similar foam or sponge material. Alternatively the resilient support means may be in the form of one or more compression springs which are mounted on the underside of the sheet member.

Patented Oct. 3, 1967 ice Though our web support can itself be supported in any suitable manner it may be conveniently supported by a channel section member comprising a rectangular sheet base member having two low side walls along opposite edges of the sheet, the upper part of each wall being turned inwardly substantially at right angles to the wall. Our web support is disposed in the channel member between the side walls in such a manner that each of the inturned parts overlaps a margin of the support surface, these margins conveniently being maintained in abutment with the underside of the inturned parts prior to a coating operation by virtue of slight compression of the resilient support means. In use the side walls will conveniently be either parallel or at right angles to the line of motion of the web. If desired the channel member may be provided with two more side walls each of which may be provided with inturned parts along the remaining two opposed edges of the base memher. When the web support is disposed so that its marginal portions are pressed against the underside of the inwardly turned parts of all four side walls the ingress of extraneous matter into the vicinity of the resilient support means is reduced or prevented.

Using our web support the web is passed continuously between the support and the applicator device, such as a doctor knife, which retains a bank of the coating composition on the web and applies a depth of coating on the web approximately equal to the clearance maintained between the web and the applicator.

During the coating operation the resilient support means permits temporary displacement of the web support necessitated by fluctuations in fabric thickness and transit speed.

Our web support may equally well be used with any of the usual web materials for example fabric, paper, sheet metal, metal or glass fibre mesh, supported or unsupported plastic sheet material. It is further readily suited, at least in one of its embodiments, to any of the usual coating compositions used.

One embodiment of our invention will now be described with reference to the accompanying drawings in which:

FIGURE 1 shows a side elevation view of one web support mounted in a suitable housing;

FIGURE 2 shows a plan view of the web support and housing shown in FIGURE 1; and

FIGURE 3 shows a section along line AA of FIG- URE 1.

The web support consists of a flat sheet member 1, one surface of which is in contact with the upper of two superimposed layers of a foam material denoted, respectively, by numerals 2 and 3. The web support is housed in a channel section member comprising a base member 4 and side walls 5 extending along opposite edges of the base member. The upper parts of the walls are inturned as at 6 to overlap and be in abutment with marginal portions of the sheet member so causing slight compression of the foam layers. The channel member is further provided with struts 7 which serve as means for mounting the device in position in preparation for a coating operation.

During a coating operation a web (not shown) is passed continuously under an applicator device ('also not shown) such as a doctor knife or rotating roller, which serves to maintain a bank of coating composition on the web and applies a coating on to the web. As the web passes under the applicator device it is maintained in contact with the free surface of the sheet member which is in a horizontal plane. The sheet material is subjected to vertical forces during the coating operation, especially when faulty or uneven webs are being coated, these forces 7 g 3 being absorbed by compression of the layers of foam material.

In a typical web support for use in the application of polyvinyl chloride coating compositions on to fabrics having a width of approximately 50 inches, the sheet member was a sheet of spring steel having the dimensions 0.012 inch x 6 inches long x 5 ft. 3 inches wide. Also each of the foam layers was a sheet of polyurethane foam having the dimensions 0.5 inch thick x 6 inches long x 5 feet 3 inches wide. The channel member was made from 16 S.W.G. mild steel sheet. It will be realised that if the fabric used is caused to pass centrally over the sheet member then the fabric (having a width of approximately 50 inches) will be bounded by marginal exposed portions of the sheet member (this having a width of 5 ft. 3 inches).

Iclaim:

In a coating apparatus, means supporting a traveling Web to be coated; said means comprising a fixed support mounting a rectangular channel member; at least one resilient foam pad carried by and Within the channel section of said member; a flexible metallic sheet overlying said pad and adapted to support the web being coated; said sheet being impervious to and resistant to reaction with the coating material; an inturned portions formed by the channel member side walls whereby to retain the pad and sheet in assembled relationship within said channel member.

References Cited UNITED STATES PATENTS 690,241 12/1901 Day 16l-40l X 824,781 7/ 1906 Fiicke 66 1,061,126 5/1913 Riley 101-407 1,131,904- 3/1915 Buckie 101407 2,285,763 6/1942 Vasel l61-40'1 X 2,405,598 8/1946 Miller 83659 X 2,587,220 2/ 1952 Ribando 28 1-15 2,616,198 11/1952 Sewell 353 8 2,752,280 6/ 1956 Cooke et a1. 2,819,032 1/1958 Detrie et al. 2,875,435 2/ 1959 McMillan. 3,284,962 11/1966 Hott et a1. 269-310 X FOREIGN PATENTS 741,044 11/ 1955 Great Britain.

MORRIS KAPLAN, Primary Examiner. 

